Master Cylinder Questions???

So I got a used 1982 Seca650 master cylinder from another member on here. My question is, stock is 14mm bore, will 5/8 which is 15.9mm work? Will this be a problem on a 1980 XJ650? I already had a rebuild kit from a friend to fit a 650 Seca.....also the sight glass is the o ring type that is missing. It had a piece of pop/beer can cut oval to size and silicone in place The top rubber seems like it has an oval cut out of it too?? and the cover is held on with metal screws....the member I got it from is not to blame as he never got the bike going and decided to scrap it......I believe all these parts are available from Chacal? Top cover rubber, screws and the sight glass fix. I guess my main concern before I spend money on fixing it up is will this MC work?

Thanks

 

Yes the bigger bore will work, it's considered an upgrade with the increased braking pressure (from what I've read on here). I'm doing the same replacement on my 82 Maxim. Chacal has all the parts for this, I just ordered my rebuild and sight glass etc. The only issue you might have is with the stock bars (assuming you have a maxim) then this MC will not sit level due to the curve of the bars. The stock MC has a tilted reservoir.

 

My 650 is 5/8 bore, that is oem.the 14mm is probably from a single disc bike

 

I have installed flat bars as well resulting in the stock MC being tilted to far. I just wanted to make sure the 5/8 was good for single front brake. I'm in the process of restoring my 650 and the front brakes are getting completely redone with braided lines and full rebuilds, mc and caliper.

 

You should be good then!

 

Nice build jayrodoh. I guess it will have to be an order to chacal then for glass and rubber cover. Did you order the silicon from him as well? I have the permatex black rtv silicone at home already.

 

I'm no expert...for sure...but as bad as that looks, why not go with this..........

http://www.ebay.com/itm/Yamaha-XJ750-XS750-Vriago-Vstar-YZ-Venture-16mm-Brake-Master-Cylinder-Black-/291462047564?fits=Model:XJ650&hash=item43dc7de74c:g:iZEAAOSwv0tVUYWu&vxp=mtr&rmvSB=true

I bought my XJ650RJ recently and I believe this is what is on it, mine is definitely aftermarket, just a thought.

 

I did not. I have tons of RTV at home. It's not the brand he sells but I will do some tests. I don't mind spending money on good parts, but $9 on RTV for one tiny application.

Thanks! Slow but I'm in no rush.

I considered buying a new aftermarket one, but I wanted the correct look and the Yamaha on the top.

 

Cause this one is Nissin and says "YAMAHA" on the top. Really that's it. Made in Japan not China, that one says 'assembled' in California. I like fixing old as well, not to mention I already had the rebuild kit from a friend that fits. Once it is soda blasted, cleaned painted and rebuilt I will be about $120 into it. That is not bad for nissin. I will post pics when its done, and how much $ it cost.

 

Ha...gotcha...it is more fun to rebuild and make it look like new, and in the end it will be an original.

 

Agreed. His master cylinder should be put onto the "don't do that" shelf, and replaced with a better one.
Original Yamaha master cylinders are only an Ebay search away, and the vast majority wont' be hacked up pieces of crap.

Chacal sells replacement sight glasses. Use clear RTV to put the glass in place.

 

Naaaah. I see nothing (gouging, deep scraps, broken or missing pieces) that would suggest this m/c can't be cleaned, painted and rebuilt.

Gary H.

 

It really looks worst than it is. Im sure that once it is cleaned up and painted all will be awesome. I have started talks with chacal to get the rubber and glass. So clear rtv makes sense for the glass.

 

That's part of the fun.

Gary H.

 

Only thing to consider is a larger bore will move more fluid but will require more force due to change in mechanical advantage. You will get a very short pull on lever to engage brake and resulting in less "feel" at the lever.